From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Tue, 18 Jun 2019 17:41:27 +0000 (+0100)
Subject: mtu: Discard over-mtu packets
X-Git-Tag: hippotat/1.0.0~55^2~1
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=03c02c85656280802dffebcace1698877e89aa60;p=hippotat.git

mtu: Discard over-mtu packets

There is no authentication of packet data.  Bad captive portals
etc. can send garbage bad enough to overflow the mtu and cause the
client to crash.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/hippotatlib/__init__.py b/hippotatlib/__init__.py
index 6423ba3..91696b1 100644
--- a/hippotatlib/__init__.py
+++ b/hippotatlib/__init__.py
@@ -232,6 +232,7 @@ class SlipStreamDecoder():
     self._buffer = b''
     self._on_packet = on_packet
     self._desc = desc
+    self._mtu = mtu
     self._log('__init__')
 
   def _log(self, msg, **kwargs):
@@ -249,7 +250,7 @@ class SlipStreamDecoder():
 
   def _maybe_packet(self, packet):
     self._log('maybepacket', d=packet)
-    if len(packet):
+    if len(packet) and len(packet) <= self._mtu:
       self._on_packet(packet)
 
   def flush(self):